Mobile devices may determine their location based on the strength of signals received from devices at fixed locations, e.g., Access Points, sometimes referred to as Anchor Points since the fixed location devices and the strength of signals therefrom provide mobile devices information from which they can estimate their location. In order for mobile location determinations to be accurate, mobiles may rely on power reference maps which include expected received signal power at various geographic locations. In this way a device can determine its location from received signals.
Unfortunately, received signal power can vary at a location based on a host of factors. These factors may include the number of users, weather conditions, potential changes in a building structure, e.g., the opening or closing of a door on a floor of a building. Accordingly the use of a simple power reference map to determine, e.g., a device's location within a building, may lead to far less accurate results then may be desired.
The efficiency of methods based on fingerprint prediction maps (e.g., signal power reference maps) relies heavily on the map accuracy. Accordingly, devices are confronted with the fact that the fingerprint prediction map (signal power reference map) may also change over time so that at different times or under different conditions more than one fingerprint (expected signal strength) may correspond to a particular geographic region. If not taken into account or not correctly modeled, those potential variations may result in a considered reference map that is inaccurate.
In view of the above, it should be appreciated that in order to make accurate location determinations based on expected signal maps, e.g., signal strength maps, reliable there needs to be methods and/or apparatus that address the issue that a particular power reference map may be more or less reliable than another power reference map at a given time because of changes in one or more conditions. The conditions may include such things as number of users present, mobility of users, changes of building structure due to opening and/or closing of doors, etc. Accordingly, there is a need for methods and apparatus for generating and/or updating map reliability information and/or updating reference map related information.